This invention relates to a process for preparing perylene pigment compositions using certain amphoteric surfactants and non-pigmentary cyclic anhydrides and imides. Perylenes, including diimides of perylene-3,4,9,10-tetracarboxylic acid, can be prepared by methods known in the art. E.g., W. Herbst and K. Hunger, Industrial Organic Pigments, 2nd ed. (New York: VCH Publishers, Inc., 1997), pages 9 and 476-479; H. Zollinger, Color Chemistry (VCH Verlagsgessellschaft, 1991), pages 227-228 and 297-298; and M. A. Perkins, xe2x80x9cPyridines and Pyridonesxe2x80x9d in The Chemistry of Synthetic Dves and Pigments, ed. H. A. Lubs (Malabar, Fla.: Robert E. Krieger Publishing Company, 1955), pages 481-482; see also U.S. Pat. Nos. 4,431,806, 4,496,731, 4,797,162, 5,248,774, 5,264,034, and 5,466,807. Perylenes as initially isolated in the process of the present invention, often referred to as crude perylenes, are generally unsuitable for use as pigments and thus must be subjected to one or more additional finishing steps that modify particle size, particle shape, and/or crystal structure in such a way that provides good pigmentary quality. See, for example, K. Merkle and H. Schxc3xa4tfer, xe2x80x9cSurface Treatment of Organic Pigmentsxe2x80x9d in Pigment Handbook, Vol. III (New York: John Wiley and Sons, Inc., 1973), page 157; R. B. McKay, xe2x80x9cThe Development of Organic Pigments with Particular Reference to Physical Form and Consequent Behavior in Usexe2x80x9d in Rev. Prog. Coloration, 10, 25-32 (1979); and R. B. McKay, xe2x80x9cControl of the application performance of classical organic pigmentsxe2x80x9d in JOCCA, 89-93 (1989).
The addition of certain perylene derivatives to the ring-closure step has been reported to improve the resultant pigments. For example, U.S. Pat. No. 5,264,034 discloses the use of certain perylene bis-imides or imide-anhydrides to improve the coloristic and rheological properties of perylene pigments. U.S. Pat. No. 5,248,774 discloses certain amphoteric perylene bis-imide derivatives for use as colorants or as surface-modifying agents for known perylene pigments. U.S. Pat. No. 5,472,494 discloses the use of certain perylene mono-imide derivatives to modify the properties of organic pigments. These patents do not, however, disclose the use of amphoteric surfactants.
U.S. Pat. No. 4,496,731 discloses a stepwise preparation of N,N-dialkylated perylene pigments in which a perylene-3,4,9,10-tetracarboxylic acid dianhydride first reacts with an alkylamine to form the corresponding ring-opened dialkyldiimide that is then thermally ring closed to form the pigment. Surfactants can optionally be added before, during, or after the cyclization reaction. Although anionic and cationic surfactants are disclosed, the patent does not mention amphoteric surfactants.
U.S. Pat. Nos. 6,015,458, 6,039,769, 6,143,068, and 6,153,764 and U.S. application Ser. No. 09/491,493 disclose the preparation of perylene pigments in the presence of certain non-pigmentary cyclic arihydrides and imides. Although anionic, cationic, and non-ionic surfactants are disclosed, amphoteric surfactants are not mentioned.
The treatment of organic pigments with nitrogen-containing surfactants is also known. For example, U.S. Pat. No. 5,662,739 describes a method for improving the dispersibility of quinacridone and dioxazine pigments using certain fatty acid taurides. This patent, however, does not disclose amphoteric surfactants such as used in the present invention. European Patent Application 758,004 describes a method for improving the dispersibility for a specific pigment, Pigment Yellow 12, by carrying out the preparative coupling reaction in the presence of certain cationic and amine oxide surfactants. The European application, however, does not mention other types of pigments. U.S. Pat. No. 5,900,050 describes a method for conditioning organic pigments with nitrogen-containing amphoteric surfactants such as those used in the present invention but does not disclose their inclusion in the pigment-forming process and does not describe their the use in conjunction with cyclic anhydrides and imides.
An object of the present invention was reducing or eliminating the use of strong acids and eliminating further surface treatment steps while at the same time providing organic pigments that can be easily dispersed in plastics. It has now been found that the presence of certain amphoteric surfactants during the conversion of perylene precursors to corresponding perylene pigments and subsequent treatment with certain non-pigmentary cyclic anhydrides and imides provides pigment compositions having improved color properties and dispersability, even in the unfinished form that is initially isolated.
This invention relates a process for preparing perylene pigment compositions comprising
(a) reacting, at a temperature of less than about 25xc2x0 C. (preferably from about 0xc2x0 C. to about 20xc2x0 C.), a mixture comprising
(1) a perylene tetracarboxylic compound,
(2) at least about 0.1% by weight (preferably 0.1 to 100% by weight, more preferably 2 to 15% by weight), relative to the perylene tetracarboxylic compound, of one or more surfactants of formula (I) 
xe2x80x83wherein
R1 is a straight or branched chain C8-C30 aliphatic group or a modified straight or branched chain C8-C30 aliphatic group in which at least one carbon atom in the main chain of the aliphatic group is replaced with xe2x80x94Oxe2x80x94, xe2x80x94Sxe2x80x94, xe2x80x94CONHxe2x80x94, xe2x80x94NHCOxe2x80x94, xe2x80x94CHxe2x95x90CHxe2x80x94, xe2x80x94OSi(C1-C4 alkyl)2xe2x80x94, or optionally substituted C5-C7 cycloalkylene,
R2 is hydrogen, C1-C6 alkyl, or xe2x80x94Yxe2x80x94Zxe2x80x2,
R3 is hydrogen or C1-C6 alkyl, or R2 and R3 together are C4-C7 alkylene,
X is a direct bond or xe2x80x94NHC(xe2x95x90NH)xe2x80x94, or X and R2 taken together with the N+ form a five- to seven-membered heterocyclic ring,
Y is difunctional C1-C8 (cyclo)aliphatic,
Z is xe2x80x94COOxe2x88x92, xe2x80x94SO3xe2x88x92, xe2x80x94PO3=. 1/n Mn+ (wherein Mn+ is a hydrogen ion or an n-valent cation), or OH, and
xe2x80x83Zxe2x80x2 is xe2x80x94COOxe2x88x92. 1/n MN+, xe2x80x94SO3xe2x88x92. 1/n Mn+, or xe2x80x94PO3=.2/n Mn+ (wherein Mn+ is a hydrogen ion and/or an n-valent cation) or OH, with the proviso that Zxe2x80x2 and Z cannot both be OH,
(3) an equivalent excess, relative to the amount of the perylene tetracarboxylic compound, of ammonia or a primary amine having the formula RAxe2x80x94NH2, wherein RA is C1-C6 alkyl, C7-C16 aralkyl, or C6-C10 aryl, and
(4) 0 to about 100 parts by weight, per part by weight of the perylene tetracarboxylic compound, of a solvent (preferably water),
xe2x80x83to form a perylene intermediate;
(b) heating the perylene intermediate at a temperature of about 50xc2x0 C. to about 250xc2x0 C. (preferably from about 120xc2x0 C. to about 150xc2x0 C.) in the presence of
(1) 0 to about 20% by weight (preferably 5 to 15% by weight), relative to the perylene intermediate, of a non-pigmentary cyclic anhydride or imide having the formula (II) 
xe2x80x83wherein
W is O or NR4,
R4 is hydrogen, a metal, C1-C6 alkyl, C5-C8 cycloalkyl, C7-C16 aralkyl, C6-C10 aryl, or xe2x80x94Alkxe2x80x94X,
R5, R6, and R7 are independently hydrogen, C1-C6 alkyl, C7-C16 aralkyl, or C6-C10 aryl, or R5 and R6 together are fused-on rings (preferably fused-on cycloalkane or aromatic rings) and R7 is hydrogen, C1-C6 alkyl, C7-C16 aralkyl, or C6-C10 aryl, or R5, R6, and R7 together are fused-on rings (preferably fused-on cycloalkane or aromatic rings),
the dotted line is an optional double bond representing R5xe2x80x94Cxe2x95x90Cxe2x80x94R6 or R6xe2x80x94Cxe2x95x90Cxe2x80x94R7 (including a formal double bond of any fused-on aromatic ring formed by R5 and R6 taken together or by R5, R6, and R7 taken together),
Alk is C1-C18 alkylene or C5-C8 cycloalkylene, and
X is
(i) an anionic group selected from xe2x80x94SO3xe2x88x92, xe2x80x94COOxe2x88x92, xe2x80x94PO3=, xe2x80x94PO(ORx)Oxe2x88x92 (wherein Rx is C1-C6 alkyl), xe2x80x94Oxe2x80x94PO3=, and xe2x80x94Oxe2x80x94PO(ORy)Oxe2x88x92 (wherein Ry is C1-C6 alkyl), each such anionic group being electrically balanced with a stoichiometric amount of a cation (preferably a hydrogen, metal, and/or ammonium ion),
(ii) a cationic group having the formula xe2x80x94NRaRbRc+ (wherein Ra, Rb, and Rc, are independently hydrogen, C1-C6 alkyl, C7-C16 aralkyl, or C6-C10 aryl), each such cationic group being electrically balanced with a stoichiometric amount of an anion (preferably halide, sulfate, phosphate, nitrate, mesylate, or tosylate or, less preferably, hydroxide),
(iii) NRdRe, wherein Rd is hydrogen, C1-C6 alkyl, C7-C16 aralkyl, C6-C10 aryl, C2-C6 alkanoyl, C7-C11, aroyl, or sulfonyl and Re is hydrogen, C1-C6 alkyl, C7-C16 aralkyl, or C6-C10 aryl,
(iv) ORf, wherein Rf is hydrogen, C1-C6 alkyl, or C6-C10 aryl,
(v) COORg, wherein R9 is C1-C6 alkyl, C7-C16 aralkyl, or C6-C10 aryl,
(vi) sulfonyl, or
(vii) C6-C10 aryl; and
(2) 0 to about 30 parts by weight (preferably 7 to 20 parts by weight), relative to the perylene intermediate, of a solvent,
xe2x80x83thereby forming the perylene pigment composition; and
(c) collecting the perylene pigment composition.
The invention further relates to perylene pigment compositions prepared in this manner.
Perylene tetracarboxylic compounds that can be used for the preparation of the pigmentary perylene compositions of the present invention include various carboxylic acids, carboxylic esters, carboxamides, cyclic anhydrides, and/or cyclic imides of formula (III) 
wherein
E1 and E3 are independently OR or NRxe2x80x2Rxe2x80x3 and E2 and E4 are independently OR, or E1 and E2 together are 0 or NA1 and E3 and E4 together are O or NA2,
each R is independently hydrogen (i.e., for free acid groups), a metal or ammonium cation (i.e., for salts), C1-C6 alkyl (i.e., for alkyl esters), C7-C16 aralkyl (i.e., for aralkyl esters), or C6-C10 aryl (i.e., for aryl esters),
each Rxe2x80x2 and Rxe2x80x3 is independently hydrogen, C1-C6.alkyl, or C7-C16 aralkyl,
A1 and A2 are independently (but are preferably identically) hydrogen, a metal, C1-C6 alkyl or substituted C1-C6 alkyl, C5-C8 cycloalkyl or substituted C5-C8 cycloalkyl, C7-C16 aralkyl or substituted C7-C16 aralkyl, or C6-C10 aryl or substituted C6-C10 aryl,
B is C1-C6 alkyl, C1-C6 alkoxy, a sulfonyl group, amino, ammonium, hydroxy, nitro, or halogen, and
p is zero or an integer of from 1 to 8.
Preferred perylene tetracarboxylic compounds of component (a)(1) are symmetrical perylene bis-anhydrides in which E1 and E2 together and E3 and E4together are oxygen atoms. Preferred perylene tetracarboxylic compounds have no aromatic ring substituents B (i.e., p is zero), but substituted perylene tetracarboxylic compounds in which at least one of the eight substitutable aromatic ring carbon atoms of the perylene moiety has at least one group B (i.e., where p is not zero) are also suitable. Some of the perylene tetracarboxylic compounds can themselves be pigments but it is not necessary for the compounds to be pigments as long as the ultimate perylene pigment composition is pigmentary.
When used to describe the perylene tetracarboxylic compounds used in step (a), the term xe2x80x9cC1-C6 alkylxe2x80x9d refers to straight or branched chain aliphatic hydrocarbon groups having from 1 to 6 carbon atoms. Examples of C1-C6 alkyl are methyl, ethyl, propyl, butyl, pentyl, hexyl, and the isomeric forms thereof. The term xe2x80x9cC5-C8 cycloalkylxe2x80x9d refers to cycloaliphatic hydrocarbon groups having from 5 to 8 carbon atoms. Examples of C5-C8 cycloalkyl are cyclopentyl, cyclohexyl, cycloheptyl, and cyclooctyl. The term xe2x80x9cC6-C10 arylxe2x80x9d refers to phenyl and 1- or 2-naphthyl. The term xe2x80x9cC7-C16 aralkylxe2x80x9d refers to C1-C6 alkyl substituted with C6-C10 aryl such that the total number of carbon atoms is from 7 to 16. Examples of C7-C16 aralkyl are benzyl, phenethyl, and naphthylmethyl. Substituted alkyl groups are those in which one or more carbon atoms are substituted with alkoxy, halogen, hydroxy (including tautomeric oxo forms), alkoxycarbonyl, aryloxycarbonyl, cyano, and nitro as defined herein. Substituted aryl and aralkyl groups are those in which one or more carbon atoms are substituted with alkyl, alkoxy, halogen, hydroxy (including tautomeric oxo forms), alkoxycarbonyl, aryloxycarbonyl, cyano, and nitro as defined herein.,The term xe2x80x9cC1-C6 alkoxyxe2x80x9d refers to straight or branched chain alkyl oxy groups having from 1 to 6 carbon atoms. Examples of C1-C6 alkoxy are methoxy, ethoxy, propoxy, butoxy, pentyloxy, hexyloxy, and the isomeric forms thereof. The term xe2x80x9csulfonyl groupxe2x80x9d refers to xe2x80x94SO2xe2x80x94Ri groups, such as alkylsulfonyl (in which Ri is alkyl; for example, methylsulfonyl or ethanesulfonyl), arylsulfonyl (in which Ri is aryl; for example, phenylsulfonyl, 1- or 2-naphthylsulfonyl, and substituted forms such as toluenesulfonyl), sulfoxyl and corresponding esters (in which Ri is OH, alkoxy, cycloalkoxy, aralkoxy, aryloxy), and sulfonamides (in which Ri is xe2x80x94NRiiRiii wherein Rii and Riii are independently hydrogen, alkyl, cycloalkyl, aralkyl, or aryl). The terms xe2x80x9caminoxe2x80x9d and xe2x80x9cammoniumxe2x80x9d refer respectively to xe2x80x94NRivRv and xe2x80x94NRivRvRvi+ in which Riv, Rv, and Rvi are independently hydrogen, C1-C6 alkyl, or C7-C16 aralkyl and each ammonium group is electrically balanced with a stoichiometric amount of an anion. The term xe2x80x9chalogenxe2x80x9d includes fluorine, chlorine, bromine, and iodine.
It is possible to use salt forms of the perylene tetracarboxylic compounds if at least one of groups E1, E2, E3, and E4 of formula (III) represents a carboxylate anion or an imide form. Suitable carboxylic salts are those in which each anionic carboxylate anion is electrically balanced with a 1/n molar equivalents of an n-valent cation Mn+ (such as Li+, Na+, K+, Mg++, Ca++, Ba++, Al+++, Fe++, or Fe+++) or an ammonium ion having the formula RIRIIRIIIRIVN+ (wherein RI, RII, RIII, and RIV are independently hydrogen, C1-C6 alkyl, C1-C6 hydroxyalkyl, or C7-C16 aralkyl). In general, free acids in which at least one of E1, E2, E3, and E4 is OH are initially added to the reaction mixture but are converted to corresponding amine salts by an in situ acid-base reaction with the ammonia or primary amine RAxe2x80x94NH2. Suitable imide salts of formula (III) are perylenes in which at least one of A1 or A2 represents 1/n molar equivalents of an n-valent cation Mn+ (such as Li+, Na+, K+, Mg++, Ca++, Ba++, Al+++, Fe++, or Fe+++). Such salts are formed whenever imides of formula (III) in which A1 and/or A2 is hydrogen are exposed to strongly basic media, either during the reaction conditions used to prepare the perylene imide or by addition of a strong base.
The perylene tetracarboxylic compounds described above, some of which are crude or conditioned perylene pigments and some of which are precursors of perylene pigment, can be prepared by any of various methods known in the art. E.g., W. Herbst and K. Hunger, Industrial Organic Pigments, 2nd ed. (New York: VCH Publishers, Inc., 1997), pages 476479; H. Zollinger, Color Chemistry (VCH Verlagsgessellschaft, 1991), pages 227-228; M. A. Perkins, xe2x80x9cPyridines and Pyridonesxe2x80x9d in The Chemistry of Synthetic Dyes and Pigments, ed. H. A. Lubs (Malabar, Fla.: Robert E. Krieger. Publishing Company, 1955), pages 481-482; and F. Graser, xe2x80x9cPerylenesxe2x80x9d in Pigment Handbook, 2nd edition, Vol. III (New York: John Wiley and Sons, Inc., 1988), pages 653-658.
A critical feature of the invention is the addition of certain nitrogen-containing amphoteric surfactants before or during the initial reaction of the perylene tetracarboxylic compound with ammonia or a primary amine RAxe2x80x94H2. Suitable amphoteric surfactants are compounds represented by formula (I) 
in which R1, R2, R3, X, Y, and Z are defined as above. One skilled in the art would, of course, understand that when at least one of R2 or R3 represents hydrogen, compounds represented by formula (I) may not actually exist in the zwiterionic form represented. That is, depending on the relative PKa values for the nitrogen atom and the carboxyl, sulfonyl, or phosponyl functions of groups Z and/or Zxe2x80x2 (as well as on the pH of the reaction mixture), the nitrogen atom may actually be deprotonated. For example, exposure to the basic reaction medium may deprotonate the nitrogen atom. As used herein, formula (I) is intended to include all such species.
The term xe2x80x9cC8-C30 aliphaticxe2x80x9d as used herein with respect to the descriptions of the surfactants refers to straight or branched chain aliphatic hydrocarbon groups having from 8 to 30 carbon atoms that can optionally be modified by replacing one or more carbon atoms in the main chain with xe2x80x94Oxe2x80x94, xe2x80x94Sxe2x80x94, xe2x80x94CONHxe2x80x94, xe2x80x94NHCOxe2x80x94, xe2x80x94CHxe2x95x90CHxe2x80x94, xe2x80x94OSi(alkyl)2xe2x80x94, or C5-C7 cycloalkylene in a chemically reasonable manner. When two or more such groups are present, they must, of course, also be present in chemically reasonable combinations. For example, heteroatoms are preferably not located adjacent to each other or, when X is a direct bond, adjacent to the N+ of formula (I). Furthermore, xe2x80x94Oxe2x80x94, xe2x80x94Sxe2x80x94, xe2x80x94CONHxe2x80x94, and xe2x80x94NHCOxe2x80x94groups cannot be attached directly to the N+ of formula (I). In addition to optional branching (which, in effect, corresponds to alkyl substitution of a linear chain), the C8-C30 aliphatic groups (including any xe2x80x94CHxe2x95x90CHxe2x80x94and C5-C7 cycloalkylene) can be substituted with groups such as C1-C6 alkoxy, halogen (especially fluorine in xe2x80x94CF2xe2x80x94 groups), hydroxy, oxo (i.e., as a keto oxygen), (C1-C6 alkoxy)carbonyl, (C6-C10 aryloxy)carbonyl, and cyano. Suitable C8-C30 aliphatic groups include alkyl groups such as octyl, decyl, undecyl, lauryl (i.e., dodecyl), myristyl (i.e., tetradecyl), cetyl (i.e., hexadecyl), stearyl (i.e., octadecyl), eicosanyl, and docosanyl, as well as isomeric forms thereof; corresponding alkenyl, alkadienyl, and alkatrienyl groups such as 8-heptadecenyl or 9-octadecenyl (as its oleyl Z-isomer or elaidyl E-isomer); amidoalkyl groups such as cocamidoalkyl (i.e., coconut fatty acid amides of aminoalkyl groups, particularly cocamidopropyl) and ricinoleamidoalkyl (particularly ricinoleamidopropyl); and polyethers such as polyalkylenoxyalkyl (particularly polyethylenoxyethyl or polypropylenoxypropyl). Particularly preferred C8-C30 aliphatic groups include cocamidopropyl, lauryl, stearyl, 8-heptadecenyl, and oleyl. It is also possible, although not preferred, to replace some or all of the main-chain carbon atoms of group R1 with xe2x80x94OSi(C1-C4 alkyl)2xe2x80x94 groups, which means that the term xe2x80x9cC8-C30 aliphaticxe2x80x9d as used herein also includes polysiloxane groups in which silicon and oxygen atoms are not attached directly to the nitrogen atom of compounds of formula (I) but are instead attached through one or more intervening carbon atoms.
The term xe2x80x9cdifunctional C1-C8 (cyclo)aliphaticxe2x80x9d as used herein with respect to the definition of Y in the surfactants refers to straight or branched chain difunctional aliphatic hydrocarbon groups having from 1 to 8 carbon atoms and to cyclic hydrocarbon groups having 5 to 8 ring carbon atoms, as well as to difunctional C5-C7 cycloaliphatic groups that can be attached to either or both of group Z and the nitrogen atom of compounds of formula (I) through methylene, ethylene, or propylene groups, provided that the total number of main-chain and ring carbon atoms does not exceed eight. Examples of difunctional C1-C8 (cyclo)aliphatic groups are C1-C8 alkylene, such as propylene, butylene, pentylene, hexylene, heptylene, and octylene (and alkyl-substituted derivatives up to a total of eight carbon atoms), and C5-C8 cycloalkylene, such as 1,2- and 1,3-cyclopentylene, 1,2-, 1,3-, and 1,4-cyclohexylene, and 1,2-, 1,3-, and 1,4-cycloheptylene. Carbon-carbon double bonds can also be present in the chain as long as they are not adjacent to the N+ of formula (I) or to OH. Although generally not preferred, it is also possible to replace one or more carbon atoms in the aliphatic chain and/or cycloaliphatic ring with heteroatoms such as N (e.g., as NH or N-alkyl), O, or S as long as such heteroatoms are not located adjacent to each other or to the N+ and Z (and/or optional Zxe2x80x2) of formula (I). Preferred difunctional (cyclo)aliphatic groups are C1-C6 alkylene groups, especially methylene and ethylene groups.
The term xe2x80x9cC1-C6 alkylxe2x80x9d refers to straight or branched chain aliphatic hydrocarbon groups having from 1 to 6 carbon atoms, also referred to as lower alkyl. Examples of C1-C6 alkyl are methyl, ethyl, propyl, butyl, pentyl, hexyl, and the isomeric forms thereof. The term xe2x80x9cC1-C6 alkoxyxe2x80x9d refers to straight or branched chain alkyl oxy groups having from 1 to 6 carbon atoms. Examples of C1-C6 alkoxy are methoxy, ethoxy, propoxy, butoxy, pentyloxy, hexyloxy, and the isomeric forms thereof. The term xe2x80x9cC7-C16 aralkylxe2x80x9d refers to C1-C6 alkyl substituted with C6-C10 aryl such that the total number of carbon atoms is from 7 to 16. Examples of C7-C16 aralkyl are benzyl, phenethyl, and naphthylmethyl. The term xe2x80x9c(C1-C6 alkoxy)carbonylxe2x80x9d refers to straight or branched chain alkoxycarbonyl groups having from 1 to 6 carbon atoms in the alkoxy portion. Examples of (C1-C6 alkoxy)carbonyl are methoxycarbonyl, ethoxycarbonyl, propoxycarbonyl, butoxycarbonyl, pentyloxycarbonyl, hexyloxycarbonyl, and the isomeric forms thereof. The term xe2x80x9c(C6-C10 aryloxy)carbonylxe2x80x9d refers to phenoxycarbonyl and 1- or 2-naphthoxycarbonyl, in which the aryl portion can optionally be further substituted with halogen, alkyl, alkoxy, alkoxycarbonyl, or nitro. Examples of halogen are fluorine, chlorine, bromine, and iodine.
Surfactants of formula (I) that contain cations include compounds of formula (I) in which Z is xe2x80x94PO3=.1/n Mn+ and/or in which R2 is xe2x80x94Yxe2x80x94COOxe2x88x92.1/n Mn+, xe2x80x94Yxe2x80x94SO3xe2x88x92.1/n Mn+, or xe2x80x94Yxe2x80x94PO3=.2/n Mn+, where Mn+ in each case is a hydrogen ion and/or an n-valent cation. Suitable cations include metal ions, such as alkali metal ions (e.g., lithium, sodium, or potassium ions), alkaline earth ions (e.g., magnesium or calcium ions), aluminum ions, iron(II) or iron(III) ions, and ammonium ions such as RIRIIRIIIRIVN+ (wherein RI, RII, RIII, and RIV are independently hydrogen, C1-C6 alkyl, C1-C6 hydroxyalkyl, C7-C16 aralkyl, and the like, such as NH4+).
Surfactants of formula (I) that do not contain heterocyclic rings formed by X and R2 taken together are generally more preferred than those containing heterocyclic rings.
Preferred non-cyclic surfactants of formula (I) are those in which R1 is C8-C30 aliphatic or modified C8-C30 aliphatic in which at least one carbon atom in the main chain is replaced with xe2x80x94Oxe2x80x94, xe2x80x94CONHxe2x80x94, xe2x80x94NHCOxe2x80x94, or xe2x80x94CHxe2x95x90CHxe2x80x94; R2 and R3 are independently hydrogen or C1-C6 alkyl (preferably an alkyl group such as methyl); X is a direct bond or xe2x80x94NHC(xe2x95x90NH)xe2x80x94; Y is C1-C6 alkylene (preferably methylene or ethylene); and Z is xe2x80x94COOxe2x88x92, or xe2x80x94SO3xe2x88x92. Especially preferred surfactants of formula (I) are cocamidopropyl betaine, an amphoteric surfactant in which R1 is cocamidopropyl, R2 and R3 are methyl, X is a direct bond, Y is methylene, and Z is xe2x80x94COOxe2x88x92, and N-3-(cocamido)propyl-N-(2-hydroxy-3-sulfopropyl)-N,N-dimethylbetaine, an amphoteric surfactant in which R1 is cocamidopropyl, R2 and R3 are methyl, X is a direct bond, Y is 2-hydroxypropyl, and Z is xe2x80x94SO3xe2x88x92.
Cyclic surfactants of formula (I), in which X and R2 together with the N+ forms five- to seven-membered rings, are heterocyclic compounds containing at least the one ring nitrogen atom shown in the formula. Group X of such heterocyclic compounds is not a direct bond but must always contain at least one atom such that group R1 is not connected directly to the nitrogen atom shown in formula (I). Group X can contain more than one such atom as long as the resultant heterocyclic ring contains no more than seven ring atoms. For example, group X can be groups having the formulas 
and the like, thereby forming heterocyclic rings that can be represented by the following formulas 
and the like (in which R1, R3, Y, and Z are defined as above and R2 completes a five- to seven-membered ring). The heterocyclic moiety can be unsaturated, including being an aromatic ring as long as group Y is not attached to an aromatic quaternary ring nitrogen. The heterocyclic moiety can also contain additional heteroatoms such as N, O, or S in place of one or more ring carbon atoms, preferably such that no two heteroatoms are directly bonded to each other. Heterocyclic ring systems that can be incorporated into surfactants of formula (I) include imidazolines, imidazoles, oxazolidines, oxazolines, and oxazoles. Preferred heterocyclic ring systems are imidazolines in which group R1 is attached to the C-2 ring carbon atom and Y is attached to one of the ring nitrogen atoms. A particularly preferred surfactant containing such heterocyclic moieties is 4,5-dihydro-1-(hydroxyethyl)-1(or 3)-(2-hydroxy-3-sulfopropyl)-2-norcocoalkylimidazolinium inner salt, an amphoteric compound within the scope of formula (I) and represented by one or both of the following formulas 
where R represents norcocoalkyl.
Mixtures of the surfactants described above are, of course, also suitable.
Solvents that can be used in step (a) are liquids that are capable of dissolving and/or suspending the components of the reaction mixture without significantly decomposing or otherwise reacting during the reaction. Examples of suitable solvents include water; monofunctional alcohols, particularly lower alkanols such as methanol, ethanol, butanol, pentanol, hexanol, and isomeric forms thereof; amides such as dimethylformamide and dimethylacetamide; ketones and ketone alcohols such as acetone and diacetone alcohol; ethers such as tetrahydrofuran and dioxane; alkylene glycols and thioglycols such as ethylene glycol, propylene glycol, butylene glycol, triethylene glycol, hexylene glycol, diethylene glycol, and thiodiglycol; polyalkylene glycols, such as polyethylene glycol and polypropylene glycol; other polypls, such as glycerol and 1,2,6-hexanetriol; lower alkyl ethers of polyhydric alcohols, such as 2-methoxyethanol, 2-(2-methoxyethoxy)ethanol, 2-[2-(2-methoxyethoxy)ethoxy]ethanol, and 2-[2-(2-ethoxyethoxy)ethoxy]ethanol; aromatic and heteroaromatic liquids, such as benzene, pyridine, and quinoline; and other such organic liquids known in the art. Water is a particularly preferred solvent. Other solvents can, of course, also often be used, but it is generally advisable to avoid solvents that can react with the reactive components. The quantity of solvent is generally not critical but should be an amount sufficient to dissolve or suspend the components of the reaction mixture but not so large as to require removal of excessive amounts after the process or any of the individual steps is complete. Typical quantities of solvent range from about 5 to about 30 parts by weight (preferably 7 to 20 parts by weight) relative to the amount of the perylene tetracarboxylic compound.
The mixture prepared in step (a) is maintained at temperatures that permit an initial reaction with the perylene tetracarboxylic compound to form a perylene intermediate without proceeding to the final perylene product. In general, temperature below about 25xc2x0 C. (preferably about 0xc2x0 C. to about 20xc2x0 C.) are sufficient to allow conversion of carboxylic esters or cyclic anhydrides to corresponding amide intermediates (as the amine carboxylate salts) without significant further conversion to the ring-closed perylene imide products. When using carboxamide starting materials, the intermediate may actually be the same as the starting material.
The primary amines used in step (a) have the formula RAxe2x80x94NH2 in which RA is C1-C6 alkyl, C7-C16 aralkyl, or C6-C10 aryl. Examples of suitable primary amines include alkylamines such as methyl amine, ethyl amine, propyl amine, butyl amine, pentyl amine, hexyl amine, and isomeric forms thereof; aralkylamines such as benzylamine and phenethylamine; and arylamines such as aniline, anisidine, phenetidine, toluidine, and various xylidine isomers. It is necessary.to use at least a slight excess of ammonia or amine relative. to the anhydride and/or imide groups of the perylene tetracarboxylic compound. In general, about 1.1 to about 10 moles (preferably 1.5 to 5 moles) of ammonia or primary amine is used per mole of the anhydride and imide groups of the perylene tetracarboxylic compound. Although generally not preferred, it is possible to use larger quantities of ammonia or primary amine, which, if liquid under the reaction conditions, can even serve as solvent or as co-solvent.
The desired perylene bis-imide pigment composition is formed in step (b) by ring closing the perylene intermediate at a temperature of about 50xc2x0 C. to about 250xc2x0 C. (preferably from about 120xc2x0 C. to about 150xc2x0 C.) until reaction is complete, typically a period of about two to six hours.
An optional feature of step (b) is the use of non-pigmentary cyclic anhydrides or imides of formula (II). The term xe2x80x9cnon-pigmentaryxe2x80x9d means that the compounds are substantially colorless or are significantly less highly colored and lack good pigmentary properties in comparison to the perylene tetracarboxylic compounds and perylene pigment compositions with which they are used. That is, suitable cyclic anhydrides or imides of formula (II) would not themselves have practical utility as pigments. The term xe2x80x9csubstantially colorlessxe2x80x9d does not mean that the cyclic anhydrides or imides must be absolutely devoid of color in the visible region but instead means only that the compounds are insignificantly colored in comparison to the perylene pigments with which they are used. For example, preferred cyclic anhydrides or imides of formula (I) will exhibit molar absorptivities less (preferably at least about an order of magnitude less) than those of the perylene precursors and perylene pigment compositions with which theyare used.
When used to describe the non-pigmentary cyclic anhydrides or imides of formula (II) (including the compounds described below), the terms xe2x80x9cC1-C6 alkyl,xe2x80x9d xe2x80x9cC5-C8 cycloalkyl,xe2x80x9d xe2x80x9cC7-C16 aralkyl,xe2x80x9d xe2x80x9cC6-C10 aryl,xe2x80x9d xe2x80x9cC1-C6 alkoxy,xe2x80x9d xe2x80x9csulfonyl group,xe2x80x9d xe2x80x9camino,xe2x80x9d xe2x80x9cammonium,xe2x80x9d and xe2x80x9chalogenxe2x80x9d have the same meanings as given above for the perylene tetracarboxylic compounds and amphoteric surfactants. The term xe2x80x9cC1-C18 alkylenexe2x80x9d refers to straight or branched chain aliphatic hydrocarbon groups having from 1 to 18 carbon atoms and two sites of attachment. Examples of C1-C18 alkylene are methylene, ethylene, propylene, butylene, pentylene, hexylene, and longer hydrocarbon chains, including both linear and branched chain groups. The term xe2x80x9cC5-C8 cycloalkylenexe2x80x9d refers to cycloaliphatic hydrocarbon groups having from 5 to 8 carbon atoms and two sites of attachment. Examples of C5-C8 cycloalkylene include 1,3-cyclopentylene, 1,4-cyclohexylene, and the like. The term xe2x80x9cC2-C6 alkanoylxe2x80x9d refers to straight or branched chain alkanoyl groups having from 2 to 6 carbon atoms. Examples of C2-C6 alkanoyl are acetyl, propanoyl, butanoyl, pentanoyl, hexanoyl, and the isomeric forms thereof. The term xe2x80x9cC7-C11 aroylxe2x80x9d refers to benzoyl and 1- or 2-naphthoyl in which the aryl portion can optionally be substituted as described above for xe2x80x9caryl.xe2x80x9d
Preferred cyclic anhydrides and imides are those in which R5 and R6 together form fused-on hydrocarbon rings (preferably fused-on cycloalkane and most preferably.aromatic ring systems, such as benzene or 1,2- or 2,3-naphthalene) and R7 is hydrogen, C1-C6 alkyl, C7-C16 aralkyl, or C6-C10 aryl (preferably hydrogen), or in which R5, R6, and R7 together form fused-on multiple hydrocarbon rings (most preferably polyaromatic ring systems, such as 1,8-naphthalene). Each of the fused ring systems can, of course, be ring-substituted, for example, with C1-C6 alkyl, C7-C16 aralkyl, C6-C10 aryl, C1-C6 alkoxy, sulfonyl, amino, ammon,ium, and halogen groups such as described above. For compounds of formula (I) in which W is NR4 (i.e., imides), the R4 group is preferably hydrogen, a metal, C1-C6 alkyl, or xe2x80x94Alkxe2x80x94X in which in which Alk is C1-C18 alkylene and X is xe2x80x94SO3xe2x88x92 or xe2x80x94COOxe2x88x92 electrically balanced with hydrogen or a metal ion.
Particularly preferred cyclic anhydrides and imides include naphthalene compounds of formula (IIa) 
in which W is defined as above; R8 and R9 are independently hydrogen, C1-C6 alkyl, C1-C6 alkoxy, a sulfonyl group, amino, ammonium, hydroxy, nitro, or halogen or R8 and R9 taken together are a group represented by the formula 
(wherein W is defined as before); each R10 is independently C1-C6 alkyl, C1-C6 alkoxy, a sulfonyl group, amino, ammonium, hydroxy, nitro, or halogen; and m is zero or an integer of from 1 to 4. For compounds of formula (IIa) in which W is NR4 (i.e., imides), the R4 group is preferably hydrogen, a metal, C1-C6 alkyl, or xe2x80x94Alkxe2x80x94X in which in which Alk is C1-C18 alkylene and X is xe2x80x94SO3xe2x88x92 or xe2x80x94COOxe2x88x92 electrically balanced with hydrogen or a metal ion. Examples of suitable cyclic anhydrides include naphthalic anhydride (i.e., 1,8-naphthalenedicarboxylic anhydride) and 1,4,5,8-naphthalenetetracarboxylic dianhydride. Examples of suitable cyclic imides include naphthalimide (i.e., 1,8-naphthalenedicarboximide), N-methylnaphthalimide, N-(2-sulfoethyl)naphthalimide and salts thereof, N-(2-sulfoethyl)-4-sulfonaphthalimide and salts thereof, N,Nxe2x80x2-bis(2-sulfoethyl)-1,4,5,8-naphthalenetetracarboxylic diimide and salts thereof, and N-(carboxymethyl)naphthalimide and salts thereof.
Cyclic anhydrides of formula (II) (where W is O) can be obtained commercially or by conversion of corresponding dicarboxylic acids to the anhydrides using known methods, for example, by heating or by treating with a strong acid or other dehydrating agents. E.g., A. Streitweiser, Jr. and C. H. Heathcock, Introduction to Organic Chemistry, 3rd. edition (New York: Macmillan Publishing Company, 1985), pages 495 and 866.
Imides of formula (II) (where W is NR4) can in turn be prepared from corresponding acids, esters, or anhydrides by known methods, preferably by reaction of a corresponding cyclic anhydride with at least a slight molar excess of a suitable amine. In a preferred method for preparing imides in which R4 contains no ionic groups, the anhydride and amine react in water heated at about 80xc2x0 C. to 100xc2x0 C. at ambient pressure or at temperatures of up to about 140xc2x0 C. in an autoclave or other sealed reactor, typically for about two to four hours. In a preferred method for preparing imides in which R4 contains anionic groups (e.g., carboxylate, sulfonate, or phosphonate groups), the protonated amino group of the amphoteric amine precursor is converted into a free amino group by adding an equivalent of a base (such as sodium or potassium hydroxide) to the reaction mixture, after which the reaction is carried out under essentially the same conditions as used for nonionic compounds. However, if the resultant anionic compound is water-soluble, it must be isolated, for example, by acidifying the reaction mixture and isolating the free acid, by increasing the ionic strength of the mixture and isolating the otherwise soluble metal salt (i.e., sodium or potassium),.or by precipitating the imide by adding a polyvalent metal salt (e.g., CaCl2, BaCl2, or FeCl2).
Imide salts of formula (II) in which W is NR4 and R4 is a metal can be prepared from corresponding xe2x80x9cfreexe2x80x9d imides in which R4 is hydrogen. Suitable imide salts of formula (I) are those in which each R4 represents 1/n molar equivalents of an n-valent cation Mn+ (such as Li+, Na+, K+, Mg++, Ca++, Ba++, Al+++, Fe++, or Fe+++). Such salts are formed whenever imides of formula (I) in which R4 is hydrogen are exposed to strongly basic media, either from the reaction mixture used in step (a) or by addition of a strong base to the free imide.
Suitable solvents for use in step (b) include the same types of solvents described above for in step (a). Water is a particularly preferred solvent. Other solvents can, of course, also often be used, but it is generally advisable to avoid solvents that can react with the reactive components. The quantity of solvent is generally not critical but should be an amount sufficient to dissolve or suspend the components of the reaction mixture but not so large as to require removal of excessive amounts after the reaction is complete. Typical quantities of solvent range from about 5 to about 30 parts by weight (preferably 7 to 20 parts by weight) relative to the amount of the perylene tetracarboxylic compound. Solvents may not be necessary in step (b) if one or more of components are themselves liquids or if the mixture of components can be melted without significant decomposition to undesired by-products.
Additives can optionally be added during either steps (a) or step (b). Suitable additives can be any of the customary pigment preparation additives known in the art that serve, for example, to improve color properties, lessen or avoid flocculation, increase pigment dispersion. stability, and reduce coating viscosity. Suitable additives include, for example, dispersants or surfactants other than those of the present invention and various pigment derivatives. Examples of suitable dispersants include anionic compounds, such as fatty acids (such as stearic or oleic acid), fatty acid salts (i.e., soaps such as alkali metal salts of fatty acids), fatty acid taurides or N-methytaurides, alkylbenzenesulfonates, alkylnaphthalenesulfonates, alkylphenol polyglycol ether sulfates, naphthenic acids or resin acids (such as abietic acid); cationic compounds, such as quaternary ammonium salts, fatty amines, fatty amine ethylates, and fatty amine polyglycol ethers; and nonionic compounds, such as fatty alcohol polyglycol ethers, fatty alcohol polyglycol esters, and alkylphenol polyglycol ethers. Examples of suitable pigment additives include organic pigments having one or more sulfonic acid groups, sulfonamide groups, carboxylic acid, carboxamide, and/or (hetero)aryl-containing (cyclo)aliphatic groups (such as phthalimidomethyl). Such additives can be incorporated in amounts ranging from about 0.05 to 20% by weight (preferably 1 to 10% by weight), based on the amount of pigment.
During the process of the present invention, the ammonia or primary amine may react with acid anhydrides and/or imides that are present in compounds of formula (II) to form corresponding imides in which at least some portion of group R4 is replaced with hydrogen (from ammonia) or group RA (from amine RAxe2x80x94NH2). However, regardless of whether the non-pigmentary cyclic anhydrides or imides are transformed in this manner, the perylene pigment compositions obtained by the process of the invention exhibit improved properties.
Upon completion of step (b), the reaction mixture is cooled and the pigment is collected, for example, by filtration, centrifugation, or other known methods.
The pigment composition can optionally be conditioned using methods known in the art, such as acid treatment, solvent treatment, and/or milling. Final particle size of the pigment can be controlled by varying the method of aftertreatment. For example, pigments can be made more transparent by reducing the particle size or more opaque by increasing the particle size. Suitable milling methods include dry-milling methods such as jet milling, ball milling, and the like, with or without additives, or wet-milling methods such as salt kneading, sand milling, bead milling, and the like in water or organic solvents, with or without additives.
During or after the optional conditioning step, it is often desirable to use various other optional ingredients that provide improved properties. Examples of such optional ingredients include fatty acids having at least 12 carbon atoms, such as stearic acid or behenic acid, or corresponding amides, esters, or salts, such as magnesium stearate, zinc stearate, aluminum stearate, or magnesium behenate; quaternary ammonium compounds, such as tri[(C1-C4 alkyl)benzyl]ammdnium salts; plasticizers, such as epoxidized soya bean oil; waxes, such as polyethylene wax; resin acids, such as abietic acid, rosin soap, hydrogenated or dimerized rosin; C12-C18-paraffin-disulfonic acids; alkylphenols; alcohols, such as stearyl alcohol; amines, such as laurylamine or stearylamine; and aliphatic 1,2-diols, such as dodecane-1,2-diol. Such additives can be incorporated in amounts ranging from about 0.05 to 20% by weight (preferably 1 to 10% by weight), based on the amount of pigment. The pigment compositions can also be blended (preferably by dry blending) with one or more pigment derivatives known in the art, particularly sulfonic acid, sulfonamide, and phthalimide derivatives.
Because of their light stability and migration properties, the perylene pigment compositions according to the present invention are suitable for many different pigment applications. For example, pigment compositions according to the invention can be used as the colorant (or as one of two or more colorants) for very lightfast pigmented systems. Examples include pigmented mixtures with other materials, pigment formulations, paints, printing ink, colored paper, or colored macromolecular materials. The term xe2x80x9cmixtures with other materialsxe2x80x9d is understood to include, for example, mixtures with inorganic white pigments, such as titanium dioxide (rutile) or cement, or other inorganic pigments. Examples of pigment formulations include. flushed pastes with organic liquids or pastes and dispersions with water, dispersants, and, if appropriate, preservatives. Examples of paints in which pigments of this invention can be used include, for example, physically or oxidatively drying lacquers, stoving enamels, reactive paints, two-component paints, solvent- or water-based paints, emulsion paints for weatherproof coatings, and distempers. Printing inks include those known for use in paper, textile, and tinplate printing. Suitable macromolecular substances include those of a natural origin, such as rubber; those obtained by chemical modification, such as acetyl cellulose, cellulose butyrate, or viscose; or those produced synthetically, such as polymers, polyaddition products, and polycondensates. Examples of synthetically produced macromolecular substances include plastic materials, such as polyvinyl chloride, polyvinyl acetate, and polyvinyl propionate; polyolefins, such as polyethylene and polypropylene; high molecular weight polyamides; polymers and copolymers of acrylates, methacrylates, acrylonitrile, acrylamide, butadiene, or styrene; polyurethanes; and polycarbonates. The materials pigmented with the perylene pigment compositions of the present invention can have any desired shape or form.
The pigment compositions according to this invention are highly water-resistant, oil-resistant, acid-resistant, lime-resistant, alkali-resistant, solvent-resistant, fast to over-lacquering, fast to over-spraying, fast to sublimation, heat-resistant, and resistant to vulcanizing, yet give a very good tinctorial yield and are readily dispersible (for example, in plastic materials).